A substrate processing chamber may be used to process a substrate in an energized process gas, such as a plasma, to manufacture electronic circuits, such as integrated circuit chips and displays. A conventional process chamber includes an enclosure wall that encloses a process zone in which a process gas is introduced. The process chamber may be used to deposit material on a substrate or to etch material from a substrate.
Exposed chamber components are often coated with a coating layer that may enhance the adhesion of sputtered material onto the coating to increase the erosion resistance to plasma of the underlying material. For example, a chamber component may be made from aluminum oxide or quartz and plasma coated with a coating of aluminum. These coated components often require frequent cleaning and refurbishing to retain their designed characteristics. For example, when chamber components are used in plasma vapor deposition (PVD) processes to sputter deposit material onto a substrate from a target, the sputtered material also accumulates on the surfaces of the component. The accumulated process deposits can cause thermal expansion stresses that result in delamination, cracking, and flaking of the underlying coating from the underlying structure. Then, the plasma in the chamber can penetrate through damaged areas of the coating to erode the exposed surfaces of the underlying structure, eventually leading to failure of the component.
Conventional refurbishment processes implement a “lift-off” process to remove the coating from a coated component and to clean the surface of the component. The “lift-off” process includes immersing a coated component in an alkaline solution, such as KOH, to strip or dissolve the coating and remove the underlying process deposits. This “lift-off” process yields an uncoated component. Next, the surface of the un-coated component is cleaned by immersing the surface in an acidic solution, such as a solution of HF and HNO3, to remove any remaining deposits. However, the acidic solution chemically attacks and causes damage to the surface of the component. Additionally, a subsequent coating that is applied to the damaged surface will not adhere well to the surface and may peel or flake off.
Another conventional method, such as that described in U.S. Pat. No. 6,902,628 issued to Wang et al., immerses a component having a metal coating in an acidic solution to remove a portion of the deposits from the surface of the component. The component is then immersed in an alkaline solution to remove substantially all of the metal coating. Once substantially all of the metal coating has been removed, the component may be bead blasted to roughen the surface of the component prior to reforming the metal coating. Similarly to the other conventional methods, the methods disclosed by Wang et al. result in damage to the surface of the component.
Accordingly, an improved method for cleaning a coated process chamber component is desired.